There are a number of patents which disclose fuel cells having a polymeric membrane. These include for example WO 02/38832 published May 16, 2002 in the name of the University of Alberta. This type of reference fails to disclose a ceramic suitable for use as a membrane in a fuel cell.
U.S. Pat. No. 5,139,541 issued Aug. 18, 1992 to Edlund assigned to Bend Research, Inc. discloses a composite membrane for use in separation purification of hydrogen. The membrane comprises two non-porous hydrogen permeable foils or membranes about 30 microns thick separated by an intermetallic (foil) barrier layer which prevents metallic diffusion between the two foils. The patent does not teach or suggest ceramic membranes or electrolyte.
U.S. Pat. No. 6,125,987 issued Nov. 28, 2000 to Ma, et al. assigned to Worcester Polytechnic Institute is similar except one of the metal membranes is a porous metallic membrane. Again the patent teaches against ceramics.
U.S. Pat. No. 5,229,102 issued Jul. 20, 1993 to Minet, et al. assigned to Medalert, Inc. teaches a steam reforming process conducted inside a heated metal ceramic. The ceramic is alumina. The patent fails to teach a fuel cell nor does it teach converting alkanes to alkenes. The patent teaches the reformatting of methane to mainly carbon monoxide and hydrogen. The reference teaches away from the present invention.
U.S. Pat. No. 6,821,501 issued Nov. 23, 2004 to Matzokos, et al. assigned to Shell Oil Company teaches a fuel cell using a ceramic support for the membrane. The ceramic support is typically alumina. The membrane is typically a group VIII metal, preferably Pd and Pd alloys. The feed is a vapourizable hydrocarbon and the off gas is largely hydrogen and CO2 without generating an alkene. The reference teaches away from the subject matter of the present invention.
There are a number of papers which disclose the use of BaCeO3 doped with about 15% of Y (BCY 15) as a proton conducting membrane for the dehydrogenation of propane to propylene with the production of electricity and water. The papers include:
Yu Feng, Jingli Luo, Shouyan Wang, Juni Melnik and Karl T. Chuang, “Investigation of Y-doped BaCeO3 as Electrolyte in Propane Fueled Proton Conducting Solid Oxide Fuel Cell”, Proceedings of the Fuel Cell and Hydrogen Technologies, D. Ghosh, Edt. 44th Annual Conference of Metallurgists of CIM, MET SOC, Montreal, Quebec, pp. 461-472, 2005. (Yu Feng presented this paper in the symposium of Fuel Cell and Hydrogen Technologies, 44th annual Conference of Metallurgists of CIM, Calgary, August 2005); andYu Feng, Jingli Luo, and Karl T. Chuang; “Analysis and Improvement of Chemical Stability of Y-Doped BaCeO3 as Proton-Conducting Electrolytes in C3H8—O2 Fuel Cells” which was presented at the 6th International Symposium on New Materials for Electrochemical Systems, Montreal, Jul. 9-12, 2006. As requested by the conference, the manuscript was submitted to the Journal of New Materials for Electrochemical Systems in May 2006.
These papers do not disclose the ceramic compositions of the present invention.
The paper “Conversion of Propane to Propylene in a Proton Conducting Solid Oxide Fuel Cell” by Yu Feng, Jingli Luo, and Karl T. Chuang, to be published in Fuel by Elsevier, also only discloses the use of BCY15 as a membrane. These papers do not disclose the subject matter of the present invention.
The present invention also seeks to provide a novel proton conducting ceramic useful as a membrane in a fuel cell to convert alkanes to alkenes and the membrane per se.